OCaml is a great language. We looked really seriously at using it at my startup for some critical things a while ago, when the company was very young, because some of the team knew it and we were inheriting a small code base in it. Ultimately immaturity of tooling (eg ocamlp4 vs ppx) and near total lack of library support killed it for us. (We ultimately went with C++.) Good luck trying to use gRPC in it, for example: there are like three different "protocol buffers" libraries that all implement different parts of it and which are incompatible with each other. While Clojure and Scala have their weaknesses, being on the JVM and being able to re-use all of that Java infrastructure was such a massive advantage.

OCaml seems awesome and I wish I could use it more, but don't underestimate how much time you'll spend fighting with opam (and a lot of things just aren't in opam at all, or the opam version isn't compatible with your OS, but there's an apt package for it, but oh no what is going on) and just trying to get to talk to the rest of your stack.

We didn’t. I’ve heard good things about it, but my understanding is it’s windows/mono, and we run all Linux in production, which seems like a pain to navigate. (F# is CLR right?) Maybe this isn’t that big of an issue in reality but we had a reason to specifically consider OCaml, and once we passed on it, had strong biases to otherwise avoid things considered exotic.